LAB: Configure a DNS service.

Installing a DNS service will bring you several advantages:
– you define machine names one for all in a centralized way, you can then better organize your workshops, build machines dedicated to a specific task (NFS server, LDAP server, etc),
– you don’t need to regularly edit the /etc/hosts file of each of them,
– you can use the machine names everywhere in an efficient way,
– you can now test postfix labs: this only point makes DNS service mandatory.

Besides making conversion between IP address and names, the DNS service provides the infrastructure necessary for mail management through the MX records.

Let’s install a DNS server for the example.com domain.
Install the bind package:

# yum install -y bind

Edit the /etc/named.conf file and change the ‘listen-on‘ option from 127.0.0.1 to any:

listen-on port 53 { any; };

In the same file, change the ‘allow-query‘ option from localhost to any:

allow-query { any; };

In the same file, disable the ‘dnssec-validation‘ option:

dnssec-validation no;

Still in the same file, below the ‘recursion‘ option, add the two following lines (with 192.168.1.1 being the DNS IP address of your Internet provider):

If you can’t use the system-config-network command, it’s because 1) you are not using RHEL 6/CentOS 6 or 2) this command is not installed yet.
If you are in the 2) case, type: # yum install system-config-network-tui
Each time, you want to install a command (here system-config-network) and don’t know the associated package, type: # yum whatprovides */system-config-network